There is no set GPA that the navy selects pilots for (the addage I heard was 2.0 and go swo, 2.5 and go fly) but obviously the higher you can get it the better.
If I remember correctly, there is a formula that that the Navy uses to decide who gets what for service selection. To give you a general idea, for aviation, they take your astb scores and make them count for something like 40% of the total score, and take the other 60% from gpa, major, aptitude+pt and PNS points. Of that other 60% GPA and Aptitude are weighted the most (also, the navy takes into account your nrotc class grades, which should only help you because most of them are easy.). Unless things have changes, the mins for the ASTB are 3/4/4 (AQR, PFAR and FORAR) on a scale of 1(or2) to 9 -for pilots, a high PFAR is a definate plus.
UTexas NROTC (
http://www.utexas.edu/rotc/navymarine/support/ASTB.htm) has a site that goes into the astb and how the selection formula is broken down. Here is what they have to say.
"Midshipmen from all 65 NROTC units compete on a national level for the available aviation billets. An aviation service selection score is computed for all physically qualified Midshipmen who would like to go into Naval Aviation. The top candidates are then selected. The following service selection formula will give you a rough idea of how scores are computed. IT IS NOT NECESSARILY THE ONE THAT CNET USES FOR SELECTION!
Cumulative GPA 27%
Adjusted Aptitude (Fall of 1/C Year only) 21%
(CNET statistically adjusts aptitude to normalize the subjective grading differences in the 65 NROTC units.)
Academic Major 6%
(Based on OPMIS major: Technical (47-66) is 100% of the possible points, Science and Math (36-40, 42-46, 90) is 87.5%, and Non- technical (1-35, 41, 67-89, 91-99) is 75%)
PNS Subjective Evaluation (assigned by CO) 6%
AQR 10%
PFAR (for pilots) or FOFAR (for NFOs) 20%
Other 10%
Total: 100%"
The scores I got selected with went something like:
GPA: 3.06 (non-tech)
Aptitude: 3.7
9.2 out of 10 on the PNS points
AQR: 4
PFAR: 5
FOFAR:3
Bottom line, 3.2 isn't bad and there probably nothing you can do about it being in a non-technical major so just continue to do your best on everything and hopefully things will work out for you. Remember "NEEDS OF THE NAVY..." Good luck.